The subject invention is directed toward the art of pipe couplings and, more particularly, to a coupling assembly for joining two relatively large diameter coaxial pipes or tubes made from different materials. The invention is especially suited for joining a plastic pipe to a steel pipe in a gas distribution system and will be described with reference thereto. As will become apparent, however, the invention is capable of broader application and could be used for joining other types of pipes and in a variety of different environments.
In the gas distribution industry, it is often necessary to join an end of a plastic pipe to an aligned end of a steel or cast iron metal pipe. The couplings used for this purpose must be capable of being quickly assembled to provide a perfectly sealed connection designed to resist substantial axial pull-out loads. Further, the coupling assembly must be capable of maintaining a leak-proof joint even if some axial creep of either pipe takes place. In addition to the above, it is highly desirable that a pipe coupling assembly of this nature be capable of functioning in extremely corrosive environments.
The subject invention provides a pipe coupling assembly that satisfies the above needs and provides an extremely effective joint. The assembly is relatively simple to make up and can be readily disassembled if required. The coupling includes a coupling body that has: (i) a central member; (ii) a first retaining member; and, (iii) a second retaining member. The first retaining member and the central member define a first pipe receiving region. The second retaining member and the central member define a second pipe receiving region having a tapered inner surface. A selectively constrictable clamp collar is located in the first pipe receiving region. A bolt or other actuation member is operably engaged with the clamp collar and is movable to constrict the clamp collar. A gripping collet is located in the second pipe receiving region and includes a tapered outer surface. At least one tie-bolt or other fastener extends between the retaining members and is selectively adjustable to draw the retaining members toward each other so that the tapered inner surface engages the tapered outer surface of the collet to constrict the collet radially.
One advantage of the present invention is the provision of a pipe coupling assembly specifically adapted for joining a plastic pipe to a metal pipe.
Another advantage of the present invention is the provision of a pipe coupling assembly for joining plastic to metal pipe that assures proper compression and engagement of the gaskets and gripping rings on make up.
A further object of the invention is the provision of a coupling assembly of the type described wherein a convenient and effective mechanism is employed for gripping a metal pipe end that does not require a torque wrench to ensure proper tightening and also to prevent overtightening, and that is releasable if required.
A still further object is the provision of an assembly of the general type described wherein the gasket and gripping or clamp rings are totally enclosed when the assembly is in the made-up condition.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.